GE L60, Instruction Manual, Page: 231 / 498

GE Multilin L60 Line Phase Comparison Relay 5-139
5 SETTINGS 5.5 GROUPED ELEMENTS
5
d) NEGATIVE SEQUENCE DIRECTIONAL OVERCURRENT (ANSI 67_2)
PATH: SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) NEGATIVE SEQUENCE CURRENT NEG SEQ DIR OC1
There are two Negative Sequence Directional Overcurrent protection elements available. The element provides both for-
ward and reverse fault direction indications through its output operands
NEG SEQ DIR OC1 FWD
and
NEG SEQ DIR OC1 REV
,
respectively. The output operand is asserted if the magnitude of the operating current is above a pickup level (overcurrent
unit) and the fault direction is seen as ‘forward’ or ‘reverse’, respectively (directional unit).
The overcurrent unit of the element essentially responds to the magnitude of a fundamental frequency phasor of either
the negative-sequence or zero-sequence current as per user selection. The zero-sequence current should not be mistaken
with the neutral current (factor 3 difference).
A ‘positive-sequence restraint’ is applied for better performance: a small user-programmable portion of the positive–
sequence current magnitude is subtracted from the negative- or zero-sequence current magnitude, respectively, when
forming the element operating quantity.
(EQ 5.18)
The positive-sequence restraint allows for more sensitive settings by counterbalancing spurious negative- and zero-
sequence currents resulting from:
• System unbalances under heavy load conditions.
• Transformation errors of Current Transformers (CTs).
• Fault inception and switch-off transients.
NEG SEQ DIR OC1 NEG SEQ DIR OC1
FUNCTION: Disabled
Range: Disabled, Enabled
MESSAGE
NEG SEQ DIR OC1
SOURCE: SRC 1
Range: SRC 1, SRC 2, SRC 3, SRC 4
MESSAGE
NEG SEQ DIR OC1
OFFSET: 0.00
Ω
Range: 0.00 to 250.00
Ω
in steps of 0.01
MESSAGE
NEG SEQ DIR OC1
TYPE: Neg Sequence
Range: Neg Sequence, Zero Sequence
MESSAGE
NEG SEQ DIR OC1 POS-
SEQ RESTRAINT: 0.063
Range: 0.000 to 0.500 in steps of 0.001
MESSAGE
NEG SEQ DIR OC1 FWD
ECA: 75° Lag
Range: 0 to 90° Lag in steps of 1
MESSAGE
NEG SEQ DIR OC1 FWD
LIMIT ANGLE: 90°
Range: 40 to 90° in steps of 1
MESSAGE
NEG SEQ DIR OC1 FWD
PICKUP: 0.05 pu
Range: 0.05 to 30.00 pu in steps of 0.01
MESSAGE
NEG SEQ DIR OC1 REV
LIMIT ANGLE: 90°
Range: 40 to 90° in steps of 1
MESSAGE
NEG SEQ DIR OC1 REV
PICKUP: 0.05 pu
Range: 0.05 to 30.00 pu in steps of 0.01
MESSAGE
NEG SEQ DIR OC1 BLK:
Off
Range: FlexLogic™ operand
MESSAGE
NEG SEQ DIR OC1
TARGET: Self-reset
Range: Self-reset, Latched, Disabled
MESSAGE
NEG SEQ DIR OC1
EVENTS: Disabled
Range: Disabled, Enabled
I
op
I_2 K I_1 ×
– =
or I
op
I_0 K I_1 ×
– =